Small-molecules targeting gp120 V1/V2 and V3 loops.
Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. A10140)
Rojo DR, Davey R, O'Brien WA, Ferguson MR University of Texas Medical Branch, Galveston TX, United States
Limitations of combination antiretroviral therapy with FDA-approved drugs mandate development of compounds directed at new targets, such as the HIV-1 envelope protein. Subunit gp120 of the envelope protein contains the determinants for interaction with CD4 and a chemokine receptor (co-receptor). Of the five variable domains in gp120, V3 contains critical determinants for viral tropism and V1/V2 may have a role in shielding the V3 loop and other regions important for co-receptor binding. These properties establish these domains as suitable targets for design of small molecule inhibitors. We have generated hybrid proteins containing the V1/V2 or V3 loops from the prototypical R5 strain JR-CSF grafted in the receptor binding domain (RBD) of murine leukemia virus (MLV) envelope. Based on structure information, and in order to preserve a gp120-like conformation of the loops, two different insertion points in the MLV-RBD were chosen. Analysis of the expressed proteins by ELISA found that the hybrids are reactive to conformational anti-V3 or anti-V1/V2 antibodies, indicating that the loops are properly folded. These hybrid proteins were used to screen phage-display libraries to identify small molecules with high affinity to these loops. Phages were eluted from target using pH 4.5 or pH 2.2 to select for peptides with different binding affinity. Selected sequences will be analyzed for in vitro antiretroviral activity. We expect that High affinity peptides directed against HIV-1 variable loops will disrupt virus entry by interfering with coreceptor interaction. Peptides and thioaptamers with antiretrioviral activity may be further developed to be used as anti-HIV agents that will share no cross-resistance with current drugs, and reduced toxicity, as they will not target normal cellular components.
Keywords: AEGIS, HIV Envelope Protein gp120, Antigens, CD4, HIV-1, Leukemia Virus, Murine, Enzyme-Linked Immunosorbent Assay, In Vitro, immunology
